A fleet that has lost half its squadrons withdraws only when the event roll comes up 6-8.
How it works
On an event roll of 6-8, a fleet that has lost half or more of its squadrons (rounded up) leaves the field. If both fleets qualify, each rolls a d6 with +1 for the defending fleet, +1 for more Determined squadrons, -1 for more Poorly motivated squadrons and -1 if the admiral was killed; the lower roll abandons the field.
6-8 A fleet which lost half of its squadrons or more leaves the field*